An electroconductive polymer is a polymer which exhibits electroconductivity by being allowed to have a π-conjugated structure extending along the polymer main chain. As the electroconductive polymer, poly(3,4-ethylenedioxythiophene) (PEDOT) has been known (see, for example, Patent Literature 1). In particular, PEDOT-PSS which contains polystyrene sulfonic acid (PSS) is easily applied to a base material since the PEDOT-PSS is obtained in the state of being dispersed in water, and moreover, its application has expanded since the PEDOT-PSS has excellent characteristics such as being excellent in transparency, being high in stability and being capable of providing low to high electroconductivity (see, for example, Patent Literatures 2 to 4).
Patent Literature 1: JP 2721700 B1
Patent Literature 2: JP 4532908 B1
Patent Literature 3: JP 2006-28439 A
Patent Literature 4: JP 4004214 B1
Patent Literature 5: JP 2011-501369 W
Patent Literature 6: JP 05-60422 B